The present invention relates to a display and a method of manufacturing the same. More particularly, the present invention provides a novel liquid crystal display having a relatively high transmittance and relatively high aperture ratio. The present invention also provides a method of manufacturing the same.
Rapid progress in the device performance of active matrix liquid crystal displays(xe2x80x9cLCDsxe2x80x9d) has opened a wide range of the applications, such as flat panel television(xe2x80x9cTVxe2x80x9d) systems, and high-information content monitors for portable computers.
A common type of technology used in these displays is conventional twisted nematic(xe2x80x9cTNxe2x80x9d) display mode. Conventional TN display mode, however, has intrinsic properties of narrow viewing characteristics and slow response time. Most particularly, TN has slow response time for gray scale operation.
In order to solve these limitations, various techniques. used in liquid crystal displays(i.e., LCDs) have been suggested or suggested. As merely an example, techniques such as a multi-domain TN structure, and an optically compensated birefringence(xe2x80x9cOCBxe2x80x9d) mode that compensates physical characteristics of the liquid crystal molecules have been proposed.
Although the multi-domain structure is often useful in improving the viewing angle, any enhancement of the viewing zone is generally limited. Additionally, an intrinsic property of slow response time still remains unsolved, in part, and processes for forming the multi-domain structure are often complicated and difficult to achieve. In contrast, the OCB mode has typically proved to have better electro-optic performances, including viewing characteristics and response time. The OCB mode, however, may have difficulties in controlling conformation of the liquid crystal molecules for self-compensation structure via a bias voltage.
Other technologies such as an in-plane switching (xe2x80x9cIPSxe2x80x9d) mode where electrodes for controlling the liquid crystal molecules are formed on the same substrate has been proposed. As an example, M. Oh-e, M. Ohta, S. Aratani, and K. Kondo in xe2x80x9cProceeding of the 15th International Display Research Conferencexe2x80x9d, p. 577 by Society for Information Display and the intrinsic of Television Engineer of Japan (1995) describe an IPS mode. The display with IPS mode also has numerous limitations. Since these displays often use materials that are opaque, display transmittance often decreases. In some cases, a back light with high intensity light is used, which is undesirable for lower powered portable computing applications, as well as others. Additional limitations include difficulty in manufacturing, which often involves complex planarization processes. These and other limitations are described throughout the present specification.
From the above, it is seen that an improved technique for fabricating an LCD display is highly desirable.
According to the present invention, a technique including a method and a device for the manufacture of an improved display is provided. In an exemplary embodiment, the invention increases an aperture ratio of the liquid crystal display and the transmittance thereof. In other aspects, the invention improves the topology of the structure of the lower substrate without the need of additional planarization process, which are commonly used in conventional devices.
According to one aspect of the invention, a liquid crystal display is provided. The display includes a variety of elements such as a first substrate and a second substrate, one being disposed opposite the other a first distance apart. Each substrate has an inner surface and an outer surface that is opposite the inner surface. The display also has a liquid crystal layer sandwiched between the inner surfaces of the substrates. The liquid crystal layer has a plurality of liquid crystal molecules. A first electrode is formed on the inner surface of the first substrate and has a first width. A second electrode is formed on the inner surface of the first substrate and has a second width. The second electrode is spaced apart by a second distance from the first electrode. These electrodes align the liquid crystal molecules using an electric field produced between the electrodes. The first and second electrodes are formed of a transparent conductive material(e.g., ITO). The display has the first distance that is greater than the second distance. Preferably, the first and second electrodes each has a width to such a degree that the liquid crystal molecules above the first and second electrodes are substantially aligned by the electric field.
According to another aspect of the invention, a liquid crystal display is provided. The display includes a variety of elements such as a first substrate and a second substrate, one being disposed opposite the other a first distance apart. Each substrate has an inner surface and an outer surface that is opposite the inner surface. The display also has a liquid crystal layer sandwiched between the inner surfaces of the two substrate. The liquid crystal layer has a plurality of liquid crystal molecules. A first electrode is disposed on the inner surface of the first substrate. The first electrode comprises a plurality of strips, each of the strips having a first width, and spaced apart by a second distance from another strip adjacent thereto. A second electrode is also disposed on the first substrate. The second electrode comprises a plurality of strips, each of the strips being disposed between the strips of the first electrode, having a second width, and being spaced apart by a third distance from another strip adjacent thereto, each of the strips of the second electrode being separated from each of the strips of the first electrode adjacent thereto with a fourth distance. An insulating layer is formed between the first and second electrodes. The insulating layer insulates the first electrode and the second electrode each other. The first electrode and the second electrode each is made of a transparent conductor, and the first distance is greater in length than the fourth distance. The second width is smaller than the second distance, and the first width is smaller than the third distance. Preferably, the strips of the second electrode each has a width to such a degree that the liquid crystal molecules overlying the strips of the first electrode and the strips of the second electrode are substantially aligned in the presence of the electric field produced between the strips of the first electrode and the strips of the second electrode, and the first width is smaller than the third distance.
According to a further aspect of the invention, a liquid crystal display is provided. The display includes a variety of elements such as a first substrate and a second substrate, one being disposed opposite the other a first distance apart. Each substrate has an inner surface and an outer surface that is opposite the inner surface. The display also has a liquid crystal layer sandwiched between the inner surfaces of the two substrate. The liquid crystal layer has a plurality of liquid crystal molecules. A first electrode is formed on the inner surface of the first substrate. The first electrode has a squared plate structure. An insulating layer is disposed on the inner surface of the first substrate including the first electrode. A second electrode is disposed on the insulating layer. The second electrode comprises a plurality of strips, the strips each being disposed to overlap with the first electrode and to have a first width and a second distance therebetween, wherein surface of the first electrode is partially exposed through spaces between the strips, the exposed portions of the first electrode each having a width of the second distance. The first and second electrodes each is made of a transparent conductor. The first distance between the first and second substrates is greater than a thickness of the insulating layer, and a second width and the first width each is to such a degree that the liquid crystal molecules above the exposed portions of the first electrode and the strips of the second electrode are substantially aligned by the electric field produced between the exposed portions of the second electrode and the strips of the second electrode.
According to still another aspect of the invention, a method for fabricating a liquid crystal display is provided. The method includes a variety of steps. First, a first transparent substrate is provided. Afterwards, a first transparent conductive layer is formed on the first transparent substrate. Thereafter, a first metal film is deposited on the first transparent conductive material and is then patterned to form a plurality of gate bus lines and a common signal line. Afterwards, a first transparent conductor film is deposited on the resulting structure and is then patterned to form a plurality of counter electrodes each including a plurality of strips that are orthogonal to the gate bus line. Thereafter, a gate insulator is formed on the resulting structure including the gate bus lines, common signal lines, and counter electrodes. A channel layer is formed on a selected portion of the gate insulating layer. A second transparent conductive layer is deposited on the gate insulator and is then patterned to form a plurality of pixel electrode each including a plurality of strips being arranged parallel to the strip of the counter electrode, and placed on the gate insulating layer between the strips of the counter electrode. A second metal film is deposited on the gate insulating layer and is then patterned to form a plurality of data bus lines that are orthogonal to the gate bus line, sources and drains. A first alignment layer is formed on the resulting structure.
According to even another aspect of the invention, a method for fabricating a liquid crystal display is provided. The method includes a variety of steps. First, a first transparent substrate is provided. A first transparent conductive layer is formed on the first transparent substrate and is then patterned to form a plurality of counter electrodes. A first metal film is deposited on the first transparent conductive layer and is then patterned to form a plurality of gate bus lines and a common signal line such that the common signal line is contact with each of the counter electrodes. A gate insulating layer is formed on the resulting structure including the gate bus lines, the common signal line, and the counter electrodes. A channel layer is formed on a selected portion of the gate insulating layer. A second transparent conductive layer, is deposited on the gate insulating layer and is then patterned to overlap with the counter electrode, to form a plurality of pixel electrodes. A second metal film is deposited on the gate insulating layer and is then patterned, to form a plurality of data bus lines, sources and drains. A first alignment layer is formed on the resultant structure. Here, the step for forming the gate bus lines and common signal line and the step for forming the counter electrode are exchangeable each other.